List of top Physics Questions

The percentage decrease in the weight of a body when taken to a height of \(48\) km above the surface of the earth is (Radius of the earth is \(6400\) km)
A body is rotating about its own axis. Its rotational kinetic energy is '\(x\)' and its angular momentum is '\(y\)'. Hence its moment of inertia about its own axis is
A boat crosses a river from one bank A to another bank B which is opposite. The distance between them is D. The speed of water is \(V_W\) and that of boat relative to water is \(V_B\). If \(V_B = 2V_W\), the time taken by the boat to cross the river directly along AB is \((sin30^{\circ} = \frac{1}{2})\), \((cos30^{\circ} = \frac{\sqrt{3}}{2})\)
The weight of man in lift moving in upward direction with an acceleration 'a' is \(660\) N. When the lift moves in the downward direction with the same acceleration, his weight is found to be \(380\) N. The real weight of the man when the lift is at rest is
A solid sphere rolls down from the top of an inclined plane. On reaching the bottom of the plane, its velocity is '\(V_1\)'. When the same sphere slides down from the top of the same plane of same height, its velocity on reaching the bottom is '\(V_2\)'. The ratio \(V_1:V_2\) is (neglect friction)
The percentage error in the measurement of mass of a body and its speed are \(0.73\%\) and \(1.84\%\) respectively. The percentage error in the measurement of its momentum and kinetic energy are respectively
Two identical rings A and B of same mass and radius are revolving, ring A arounds its own diameter and ring B about tangential axis in its own plane. Both the rings A and B have same rotational kinetic energy. The ratio of the angular velocity of ring B to that of ring A is
The area of parallelogram formed by vectors \(\overset{⃗}{P} = 2\hat{i}-\hat{j}+5\hat{k}\) and \(\overset{⃗}{Q} = 3\hat{i}-2\hat{j}+4\hat{k}\) is
In a transistor, comparing the doping of emitter, base and collector, the part which is heavily doped and that which is lightly doped are respectively
In the following electrical circuit, the reading in the milliammeter is
(Take knee voltage of silicon diode \(= 0.7\) V)
The Boolean expression for the given combination of logic gates is
The magnetic moment of electron due to orbital motion is proportional to
(\(n\) = principal quantum number)
A radioactive element has rate of disintegration \(16,000\) disintegrations per minute at a particular instant. After four minutes, it becomes \(2000\) disintegrations per minute. The decay constant per minute is
In biprism experiment, the maximum intensity is \(I_0\). If the path difference between the two interfering waves is \(\frac{λ}{3}\), then intensity at the point on the screen is
[\(sin30^{\circ} = cos60^{\circ} = 0.5\), \(sin60^{\circ} = cos30^{\circ} = \sqrt{3}/2\)]
If the ionisation energy for the hydrogen atom is \(13.6\) eV, then the energy required to excite it from the ground state to the next higher state is nearly
The de-Broglie wavelength of an electron moving in the \(n^{th}\) Bohr orbit of radius 'r' is
A ray of light is incident at polarising angle \(θ\) on air-glass interface. If \(λ_a\) and \(λ_g\) are the wavelengths of light in air and glass respectively then
When light of wavelength '\(λ\)' is incident on a photosensitive surface, the stopping potential is 'V'. When a light of wavelength \(1.5λ\) is incident on the same surface, the stopping potential is '\(\frac{V}{4}\)'. Threshold wavelength for the surface is
In a biprism experiment, a steady interference pattern is observed on the screen kept at a distance of 100 cm using a light of wavelength \(5000\) Å. Without changing the distance between the virtual images of the slit, the source of light is replaced by a source of wavelength \(6400\) Å. Now, to reduce the fringe width by \(20\%\) of its initial value, the screen should be moved
Two coils P and S have a mutual inductance of (\(π\)) mH. The secondary coil S has resistance \(4\,\Omega\) and self inductance \((60/π)\) mH. If the current in the primary is \(I_p = 12sin(50πt)\), then the maximum value of the current induced in coil S is [Take \(π^2 = 10\)]
The magnetic energy stored in an inductor of inductance \(4\,\text{H}\) carrying a current of \(1.5\) A is
Light travels a distance 'x' in time '\(t_0\)' in air and '\(4x\)' in time '\(t_1\)' in another denser medium. The critical angle for this medium is
When a.c. source is connected across a pure capacitor, the correct phase relation between current and emf is shown in figure.
In series LCR circuit \(R = 10\,\Omega\) and impedance is \(30\,\Omega\). An r.m.s. voltage \(210\) V, is applied across the circuit. The true power consumed in AC circuit is
A solenoid is connected to a battery so that a steady current flows through it. If an iron core is inserted into the solenoid, then the current in the coil